Add LoRa FEM LNA toggle menu support

[Quency-D]

Summary

Adds an on-device screen menu for controlling the LoRa FEM LNA using the existing fem_lna_mode configuration.

This restores the screen control that was removed from #9753 without changing the protobuf definition, FEM driver, or default LNA behavior.

Changes

• Adds FEM LNA to the on-device LoRa Actions menu.
• Only shows the option when the detected FEM supports software LNA control.
  • Heltec V4.3 with KCT8103L: option is available.
  • Heltec V4.2 and earlier with GC1109: option remains hidden because its LNA cannot be bypassed through software.
  • Boards without a LoRa FEM are unaffected.
• Provides Enabled and Disabled selections and highlights the current setting.
• Applies the selected state immediately and saves it through the existing LoRa configuration flow.
• Does not require a reboot.
• Keeps the LNA enabled by default.

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Heltec (Lora32) V3
  • Heltec V4.2 / V4.3
  • Heltec wireless tracker V2
  • Heltec mesh node t096

Hardware testing is still required before these attestations can be checked.

Summary by CodeRabbit

• New Features
  • Added a LoRa FEM LNA menu for compatible hardware.
  • Users can enable or disable FEM LNA operation directly from the LoRa settings.
  • The menu is shown only when supported hardware controls are available.
  • Changes are applied immediately and reflected in the device configuration.

[github-actions]

⚡ Try this PR in the Web Flasher

Note

Building this pull request… the flash button, badges and supported-board
list will appear here automatically once CI finishes.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: f9d52c44-dcd5-4055-b347-ae3562f3543c

📥 Commits

Reviewing files that changed from the base of the PR and between 41c5c92 and 47f80cc.

📒 Files selected for processing (2)

• src/graphics/draw/MenuHandler.cpp
• src/graphics/draw/MenuHandler.h

---

📝 Walkthrough

Walkthrough

Changes

LoRa FEM LNA menu

Layer / File(s)	Summary
Menu contract and FEM entry src/graphics/draw/MenuHandler.h, src/graphics/draw/MenuHandler.cpp	When HAS_LORA_FEM is enabled and controllable hardware is available, the LoRa menu adds the FEM LNA option and routes selection to the new menu.
FEM LNA toggle handling src/graphics/draw/MenuHandler.cpp	The new menu supports Back, Enabled, and Disabled. Valid changes update the FEM LNA configuration, apply the hardware state, reload configuration, and log the result.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: nomdetom

Sequence Diagram(s)

sequenceDiagram
  participant User
  participant menuHandler
  participant LoRaFEMInterface
  participant DeviceConfiguration
  participant Logger
  User->>menuHandler: Select FEM LNA mode
  menuHandler->>LoRaFEMInterface: Update and apply LNA state
  menuHandler->>DeviceConfiguration: Reload configuration
  menuHandler->>Logger: Log FEM LNA state

Loading

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a LoRa FEM LNA toggle menu.
Description check	✅ Passed	The description explains the purpose, behavior, hardware conditions, and implementation scope, but it contains a minor testing-attestation contradiction.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}